In the past, a game apparatus has been proposed wherein characters arranged in a virtual space are displayed on-screen such that their positions and postures are varied. Such character display technology is disclosed in the following literature, for example. Patent Literature 1: Unexamined Japanese Application KOKAI Publication No. 2002-092644
In [Patent Literature 1], technology for quickly generating an image of a character is disclosed, having an envelope model wherein polygons corresponding to skin are arranged surrounding a skeleton corresponding to bones.
If the overall position or orientation of the skeleton in a virtual space is varied, then the character moves. If the relative positions or orientations of skeleton components are varied, then the posture of the character is varied. In addition, if the coordinates of the skeleton are mirror-transformed, then the posture of a given character can be made symmetrical to the posture of another character.
If the position and posture of the character skeleton is then varied on the basis of predetermined coordinate data as time elapses from a fixed time (typically, the start time for playback of a song), then video showing the character dancing to the song can be displayed.
In addition, if position and posture relationships among a plurality of character skeletons are made to mutually overlap by translation, then video showing the characters dancing in unison as a group can be displayed.
In addition, the mirror transformation of skeleton coordinates can even be used in the case where a left-side character and a right-side character in the dancing group are dancing with symmetrical motions.
When expressing a dancing group of characters like that described above, operations such as parallel transformations and mirror transformations of coordinates are implemented.